The United States will work with other nations to develop an international code of conduct for outer space, but only if the code does not hinder U.S. national security efforts, Secretary of State Hillary Clinton announced Tuesday (Jan. 17).

Space junk and "irresponsible actors" threaten the long-term sustainability of the space environment, Clinton said in a statement released Tuesday. Such threats can be reduced and managed if the U.S. and other nations establish rules for everyone to follow, she added.

"A code of conduct will help maintain the long-term sustainability, safety, stability and security of space by establishing guidelines for the responsible use of space," Clinton said.

The European Union has been drawing up such a voluntary code for several years. As recently as last week, U.S. officials had stressed that the nation was not prepared to sign the E.U.'s draft code. [Photos: Space Junk & Cleanup Concepts]

"It’s been clear from the very beginning that we’re not going along with the code of conduct," Ellen Tauscher, undersecretary of state for arms control and international security, said Jan. 12, according to Space News. "It's too restrictive."

However, decision-makers had left open the possibility of working together to develop a version of the code more acceptable to the U.S. That's in keeping with President Barack Obama's 2010 National Space Policy, which highlighted the importance of international cooperation in the space arena.

Clinton's statement stresses that the nation won't sign any code that ties the military's hands.

"As we begin this work, the United States has made clear to our partners that we will not enter into a code of conduct that in any way constrains our national security-related activities in space or our ability to protect the United States and our allies," Clinton said.

This computer illustration depicts the density of space junk around Earth in low-Earth orbit.

NASA estimates that the cloud of orbital debris surrounding Earth contains more than 22,000 pieces as big as a softball and more than 500,000 bigger than a marble. Only 1,100 of those objects are active satellites, according to a State Department statement. This debris cloud is growing all the time as humanity launches more objects into space and these objects occasionally collide with each other.

Several high-profile events have helped thrust the space-junk problem into the public eye recently. For example, Russia's failed Mars probe Phobos-Grunt crashed to Earth Sunday (Jan. 15) after languishing in orbit around our planet for two months. On Friday (Jan. 13), the International Space Station dodged a softball-size piece of space debris.

Further, NASA's dead UARS satellite slammed into the atmosphere over the Pacific Ocean in September, and Germany's defunct ROSAT craft re-entered over the Indian Ocean a month later.

And space junk is not the only worry.

"The threats to the space environment will increase as more nations and non-state actors develop and deploy counter-space systems," the State Department's fact sheet states. "Today space systems and their supporting infrastructure face a range of man-made threats that may deny, degrade, deceive, disrupt or destroy assets."

In 2007, China intentionally destroyed a dead weather satellite with a rocket in an anti-satellite weapons test. Indian military officials have also expressed an interest in anti-satellite technology.

You can follow SPACE.com senior writer Mike Wall on Twitter: @michaeldwall. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.